diff -up celestia-1.6.1/src/celengine/frametree.h.gcc47 celestia-1.6.1/src/celengine/frametree.h
--- celestia-1.6.1/src/celengine/frametree.h.gcc47	2012-03-22 12:56:56.096087430 -0400
+++ celestia-1.6.1/src/celengine/frametree.h	2012-03-22 12:57:04.333022427 -0400
@@ -13,6 +13,7 @@
 #ifndef _CELENGINE_FRAMETREE_H_
 #define _CELENGINE_FRAMETREE_H_
 
+#include <unistd.h>
 #include <vector>
 
 class Star;
diff -up celestia-1.6.1/src/celengine/planetgrid.cpp.gcc47 celestia-1.6.1/src/celengine/planetgrid.cpp
--- celestia-1.6.1/src/celengine/planetgrid.cpp.gcc47	2012-03-22 12:53:01.496950513 -0400
+++ celestia-1.6.1/src/celengine/planetgrid.cpp	2012-03-22 12:53:08.812891865 -0400
@@ -12,6 +12,7 @@
 
 #include <cstdio>
 #include <cmath>
+#include <celmath/mathlib.h>
 #include <celmath/intersect.h>
 #include "planetgrid.h"
 #include "body.h"
